This invention relates generally to tracking the position of objects in three dimensional space, and more particularly to verifying the position of components of an object in 3-D space using a probe apparatus.
In many assembly processes of electronic devices, several different components must be assembled quickly and reliably to allow the devices to be offered to consumers at low prices. Circuit boards used in electronic devices are one of the most common multi-component parts that require such efficient assembly. Assembling printed circuit boards, often called xe2x80x9cstuffingxe2x80x9d the circuit board, typically involves placing components on a circuit board in predetermined locations and soldering the components in place. The components might include resistors, capacitors, integrated circuits, op amps, connectors, wire leads, clock crystals, inductors, or a variety of other passive and active components. Many different types of these components are often assembled on a single board and must be soldered in the correct location on the board for a board to function properly. The components can be placed and soldered by human assemblers but are more often xe2x80x9cstuffedxe2x80x9d by more automated methods. For example, a xe2x80x9cpick and placexe2x80x9d machine is a robotic device that automatically puts the various components in previously programmed positions. A xe2x80x9cwave soldererxe2x80x9d is a machine that solders many components on a circuit board in place at once. These types of tools greatly accelerate the circuit board assembly process.
Regardless of how a board is assembled, by hand or by machine, it is often important to perform quality control measures to ensure the board has the proper components in the proper locations. A board with even one component in the wrong place may function incorrectly or not at all. Errors in the assembly process can originate from a variety of sources. For example, a human assembler might have put a component in the wrong position on the circuit board. Or, a human operator might have loaded the wrong components in a pick and place machine. In many cases, different components appear very similarly and may vary only by their values or class. For example, resistors having different resistance values or capacitors having different capacitance values may appear almost identical, leading to these errors. Or, the pick and place machine may have been incorrectly programmed, leading to other errors. Regardless of why the errors occurred, the result is the same: an incorrectly placed component can result in a non-functional product. The more non-functional products resulting in an assembly process, the greater the cost of the functional products to the buyer.
Quality control procedures for circuit boards are rigorous processes in which every component on the circuit board is checked to ensure that the board has been properly assembled. Both the type of component and also the specific values of the components are checked. This is often accomplished by human operators who visually inspect the circuit boards. The process involves looking at a document, usually a xe2x80x9cbill of materialsxe2x80x9d and/or a board schematic, and confirming visually that every component on the board is correctly placed and has the correct value. This process tends to be tedious because it involves looking back and forth from the board to the documents. What is needed is a rapid way to point at a position or a component on a physical circuit board and a system that immediately reports the type and value of the proper component that is supposed to be located at the pointed position, without the operator having to look at a long list or a dense schematic drawing.
The present invention provides a system and method for checking and verifying the positions of components on an object such as a circuit board using a probe apparatus. The invention allows a significant increase in efficiency in the component verification process.
More specifically, a method for checking components of an object includes placing the object in a workspace volume of a probe apparatus. The probe apparatus is operative to provide three-dimensional position information to a computer. One of the components of the object is selected by the user using the probe apparatus, where the selected component is positioned at a particular location on the object. The selected component is compared with reference information about a correct component output using information provided by the computer. The correct component is desired to be positioned at the location of the selected component. By reviewing the displayed reference information, the user or, alternatively, the computer can determine if the selected component is of the correct type, value, or other characteristic. Preferably, the selecting is accomplished by moving a probe tip of the probe apparatus within a predetermined distance of the selected component and activating a control, such as a button.
In a different aspect of the present invention, a method provides verification information about components of an object and includes receiving position information from a probe apparatus. The position information describes a location on the object placed in a workspace volume of the probe apparatus, where a physical component is positioned at the location on the object. Reference data is accessed for a desired component layout of the object, where the reference data includes descriptive information about a component desired to be provided at the location described by the position information. At least a portion of the descriptive information about the desired component is used for a comparison between the descriptive information and the physical component positioned at the location on the object. The method is preferably repeated for each component on the object.
The object is preferably a printed circuit board and the components include circuit board components. The object is preferably located in the 3-D workspace of the probe apparatus by receiving position information from the probe apparatus describing at least two points on the object. An origin of the object is determined and correlated with the reference origin for the reference data. The descriptive information about the desired component includes a type and value of the component. The descriptive information can be output, such as by displaying the information on a display screen and/or outputting audio signals to the user. If the selected component has previously been checked, an indication is output to the user. Preferably, the user initiates a verify signal that is received by the computer when the descriptive information of the desired component matches the physical component on the object at the location. A failure signal is preferably initiated by the user when the descriptive information of the desired component does not match the physical component. The computer preferably stores data associated with the location indicating that the match exists or does not exist. A computer readable medium stores program instructions that perform steps similar to the above method.
The present invention provides an efficient, rapid way to verify that components of an object like a printed circuit board are correctly positioned. A user can quickly point to each component and receive instant, easily-viewed reference information that allows the user to verify that the component is placed correctly. The present invention also allows efficient organization of verification data to allow easy review of components and component placement errors. These and other advantages of the present invention will become apparent upon reading the following detailed descriptions and studying the various figures of the drawings.